And London is My Game Board
by gauchadeutsche
Summary: Part 6 of the A Chair in Its Proper Place series, also SEQUEL to Algebra for Detectives. Archie comes to Baker Street to spend a whole day with Sherlock...what sort of madness will ensue? Will Baker Street survive? Will Mrs. Hudson have any food left in her cupboard? Will Archie need therapy after a day with Sherlock? Read on and find out! Multichapter, complete.
1. Chapter 1

**And London is My Game Board**

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I'm back with more Sherlock + Archie bonding! This one will have at least 3 chapters, possibly 4 or 5 (I've written the beginning, the end, and a chunk of the middle, but it needs filling in on both sides). If you're lost, go back and read **Algebra for Detectives**, aka Part 3 of _A Chair in Its Proper Place_.

Chronologically, this is Part 6 of the _A Chair in Its Proper Place_ series, falling between **Morphine and Chips** and **Friendly Advice**, which I will be posting shortly.

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**1\. Cynthia's Last Resort**

_October 18, 2014_

Sherlock lay in his favorite thinking position, hands steepled under his chin. Two nicotine patches stood out against the pale skin of his arms, exposed by the wide sleeves of his dressing gown. John, after ten days of checking on Sherlock obsessively when he was home, and texting when he wasn't, had finally relaxed enough to go out. He was at Harry's for the day, leaving his best friend in the excellent care of Mrs. Hudson.

Lestrade was still refusing Sherlock fieldwork, partly due to his injury, and partly for not telling who had shot him. The detective had considered lying, several times, but nothing was convincing enough. Therefore, his week of convalescing was up and he still had no cases. Instead, he was reviewing what he knew of Magnussen in his mind palace.

_BUZZZZZZZZZ_!

Startled, Sherlock looked at his phone. He had not memorized this number or added it to his contacts, but it was one digit off from Archie's number. His mother, then.

He answered on the second buzz. "Hello, Cynthia."

"Hi, Sherlock," the secretary replied, sheepish. "Did I wake you?"

"No, not at all," he answered.

"Listen, I know you're still recovering," Cynthia said, getting to the point, "but I need to meet my ex and his solicitor in London this afternoon, and I've no one to watch Archie. I hate leaving him by himself—"

"It's no problem," Sherlock told her quickly. "Bring him 'round now, and he can spend the day with me and Mrs. Hudson. Go shopping, see your ex, have a nice dinner, and come back when you're ready."

"Really?" Cynthia Ross asked, too relieved to question Sherlock's ready acceptance. "Thanks so much, Sherlock, you're a lifesaver! I know he's been eager to see you!"

"Great, see you soon then," the man replied, and hung up after the goodbyes.

The day was looking up, Sherlock thought, ripping the patches off his arm. Archie had only called twice since his first call to the hospital, but each time revealed more about the clever little boy, and Sherlock was intrigued. No one had admired him for his brilliance until John, and perhaps The Woman, but Archie treated him with a reverence that bordered on hero worship.

It didn't hurt that Archie was capable of holding a five minute conversation without boring Sherlock, a rare gift indeed.

With a grin, Sherlock Holmes stood up—carefully—and headed for the shower. If Cynthia and Archie left their Swindon home immediately, they'd reach Baker Street in an hour and a half.

He took a long shower, washing carefully around his new scar. Mrs. Hudson came and went, leaving a tea tray laden with biscuits and today's newspaper. She really was a jewel among landladies, thought Sherlock, humming as he shampooed his hair. He finally stepped out of the shower when the hot water ran out.

After dressing in his favorite purple shirt and black trousers, Sherlock picked at his breakfast and plucked at his violin, keeping it low to avoid pulling at his injury. He was thus employed when Mrs. Hudson knocked again, ushering in Cynthia Ross and Archie Campbell.

To Sherlock's infinite amusement, little Archie was wearing dark jeans and a button-up shirt in the exact shade of purple as his own, though he wore it unbuttoned over a black T-shirt.

"Hi, Sherlock," Cynthia said, shaking his hand. "Thank you _so_, so much, really. Are you sure you'll be fine?"

"Yeah, we'll be alright," the detective answered, taking in the ink stain on her left index finger, a slight rip in the hem of her skirt, and two white dog hairs clinging to her red scarf. "We have Mrs. Hudson."

"I'm your landlady, dear, not your babysitter," said lady told him fondly, then looked down at Archie. "Have you had breakfast yet, young man?"

"Oh yeah, we had a bite at the station," Cynthia answered, "but he's having a bit of a growth spurt; always hungry, this one."

"Ah!" Mrs. Hudson said knowingly. "I have just the thing downstairs."

She went back down to her own flat, presumably in search of baked goods.

"Take all the time you need," Sherlock offered his guest. "Come back when you're ready; we'll be fine."

"Great," she replied. "Remember, Archie is allergic to—"

"Peanuts, shellfish, and soya," the detective supplied.

Cynthia smiled wryly. "You really do remember everything, don't you? Well, I suppose Archie is in good hands, then." She kissed the top of her son's head. "Behave, you. Ring me if you need anything."

"Mum, come on," he sighed, with all the exasperation of a boy who felt too old for these displays.

"Bye!"

She waved and finally left, all black trench coat, brown curls, and swishing red scarf. Mrs. Hudson appeared not a moment later, carrying a tray of scones and jam.

"Oh, those are the _good_ scones," Sherlock commented to Archie, earning a swat on the forearm from his landlady as he took one. "She only brings those out if she _really_ likes you."

"Thanks, Mrs. Hudson!" the boy said cheerily.

"You're welcome, dear. Enjoy, and don't let this one get you into any trouble!" she warned, brandishing a spoon in Sherlock's direction.

Sherlock licked a bit of raspberry jam off his finger, all innocence.

"I mean it, Sherlock! I will be checking every hour on the hour, and if I see any—any explosions, or severed heads, or guns, there will be hell to pay!"

Archie watched through a mouthful of scone, fascinated. Sherlock winked at him.

"I'll have you know, Mrs. Hudson, that Archie and I have had hours upon hours of conversation, and not once have I shown him a severed head or taught him to blow things up."

Perfectly true, of course. He'd shown Archie photos of corpses, both with their heads and without, but no severed heads.

She softened a bit. "Good. You have some common sense, then."

"He's alright, Mrs. Hudson," Archie added, cottoning on, "he helps me with my homework, you know, for school."

"Oh. Well, that's nice," Martha Hudson said, surprised. "I'll leave you to it, then."

When she closed the door, Archie and Sherlock exchanged the universal 'Mothers!' glance and went back to the scones, happy to devour every last one. It didn't take long.

"So," Sherlock said finally, once the plate was empty. "You didn't come here to do more homework, did you?"

Archie grinned. "Nah, I finished it yesterday."

"Excellent," the adult replied, clapping his large hands together.

"Can I help with one of your cases, maybe?" Archie asked hopefully.

Sherlock sighed. "I don't have any yet, unfortunately. I'm still 'recovering'," he moaned, making air quotes. "But," he added, brightening, "if you're still interested in becoming a detective, we can start your training today."

"Really?"

"Sure," the younger Holmes brother answered, getting off his chair and crossing the room to the kitchen sink in a few long strides. He washed his hands vigorously, then turned back to Archie.

"We'll start with a little field trip."

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As always, many thanks to everyone who reviewed _Algebra_ or the Chair series! I've enjoyed reading your comments and your compliments make my day. I have way too many stories going on at the moment, so I appreciate you all for coming back even with my infrequent updates and hectic work schedule. Have a lovely day, everyone!


	2. Chapter 2

**And London is My Game Board**

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Hello again! I've fallen into the black hole that is the Doctor Who fandom, but since I find the idea of DW fanfic intimidating (I've only seen New Who and the Paul McGann movie), I'm sticking to Sherlock.

And now, the field trip begins!

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**2\. Archie the Apprentice**

To Archie's great frustration, Sherlock gave no clues about where they were going. He simply ordered the boy to bundle up, and off they went, down the stairs and out to Baker Street.

"Lesson one," Sherlock said, leading Archie towards the park. "A good detective must be observant. It's a fairly nice day, so we'll see lots of people at the park. I'll show you how I use my deduction skills to read people, and see if you can do the same."

It didn't take long to reach the edge of Regent's Park, and they sat on a bench facing the lake. As Sherlock had predicted, there were quite a few people about. Some were rowing on the lake, others lazing on the grass or biking along the water.

"See that woman there?" Sherlock asked, and Archie turned to look. "If I look at her, I can read dozens of details from her face, her clothes, her expression, and all of the little things about her. What do you see?"

The woman in question was a young brunette. She lay on a blanket, propped up on her elbows as she read a book. White earbuds peeked out from under her hair, and one of her feet bobbed along to the beat of her music.

"She's a big fan of _Doctor Who_," Archie began, hesitating. "There's a TARDIS on her jumper, and she has some Circular Gallifreyan on her bag. It says..." Archie squinted. "Andrea. So she's enough of a fan to learn to write in Gallifreyan, or she knows someone who does. And that's definitely the Fourth Doctor's scarf, so she likes classic_ Who_ as well."

The detective nodded, more impressed than he'd expected to be. He had only the vaguest idea of what a TARDIS was (thanks to John), and he could make neither heads nor tails of the lines and circles embroidered on the bag, but Archie had made full use of his own knowledge, and deduced her name and some of her personal tastes from it. He was a rather brilliant little boy, and certainly observant in his own way!

"Good," he said finally, smiling encouragingly. Archie grinned. "Anything else?"

The curly-haired detective in training scratched his nose. "She might have some kind of problem with her feet," Archie added, and Sherlock's eyebrows shot up into his hairline. "I think those are orthopaedic trainers, like my godmother wears sometimes."

"Very good," Sherlock told him, now grinning openly. It was _so _refreshing to meet someone with an ounce of observational skills! Archie and Bill Wiggins were worth their weight in gold.

"What else is there?" Archie asked curiously. "What do _you _see, Sherlock?"

Sherlock took a deep breath, and began. "You mentioned her bag—it's clearly handmade, not just the embroidery, but the whole thing. She's used it for ages; it's worn through, but she's not replacing it. The overall quality of her clothes suggest that it's not for lack of money, so it's sentiment. Someone she cares about gave her that bag, and she likes that person enough to ignore the rip on the bottom corner."

Archie watched, enthralled, as Sherlock flew into deduction mode.

"She's obviously left-handed. You can tell because she turns the pages with her left hand, and she keeps her iPod on her left side. The fading tan on her left hand tells me that she was abroad somewhere sunny this past summer, and that she wore an engagement ring at the time. The ring is gone, so she broke up recently. She clearly bites her nails when she's nervous, and the large, heavy book she's reading on a Saturday morning tells me she's a student, and a serious one at that."

"You're right about the shoes—size eight, and clearly good quality trainers from a well-known orthopaedic shoe manufacturer. If she stands up and walks away while we're here, we might see _why_ she needs them, but for now, let's leave it at that."

"Wow," Archie sighed.

"You never know which details might be relevant to a case until it happens," Sherlock explained. "Sometimes a murder victim will have a wound that is impossible for a left-handed woman of a particular height to inflict, so that would help to rule her out. She might leave prints outside the house, and the rarer the shoe, the easier it is to trace. A broken engagement might be motive for something. Until you know, observe everything."

The detective's apprentice nodded faithfully.

"Look over there," Sherlock instructed, singling out a man with a dog. He stood under a tree, holding a plastic bag and waiting for his bulldog to do his business. "What do you see?"

Archie wrinkled his nose. "He's a Chelsea fan," he muttered, oozing far too much disdain for such a sweet kid. "The scarf gives him away. It looks quite old, so he probably grew up supporting them."

Sherlock didn't know enough about football to confirm or deny, but he trusted Archie's information, if not his bias.

"He's married," he went on, "'cos he's wearing a ring. He's got a mark on his nose, like he usually wears glasses."

"Good," the detective said. "Anything else?"

When Archie shook his head, Sherlock had his turn.

"See the bump on the middle finger of his right hand?" he began. "That's a callus from holding a pen. That means he writes regularly using a pen and paper rather than a laptop, and he is obviously right-handed. I see traces of a white substance on the hem of his jumper. What kind of profession requires lots of reading, writing by hand, and standing close to something that would leave a straight line of white residue?"

"He's a teacher!" Archie cried, grinning in triumph. "That's from standing against a chalkboard."

"Correct," replied Sherlock, satisfied. "You pick the next one."

Archie took his time, eyes moving from the runners, to the families with small children, to the little old ladies, gossiping on park benches. He settled on a tiny woman, seated a few meters away. A woolen hat covered her wispy white hair, and she knitted peacefully, working on what looked like the beginnings of a baby's jumper.

"That lady there," he said to Sherlock. "She has a white cat; I can see the hairs on her skirt."

Sherlock nodded in approval.

"She _had _a wedding band, but not anymore, so she's divorced or widowed," Archie went on. "She has something under her sleeve, a nicotine patch, maybe?" He squinted a bit. "So she was a smoker and is trying to quit. She's knitting something for a baby boy, so she's probably having a grandson soon."

"Anything else?" the detective asked.

"She's diabetic!" cried Archie, suddenly noticing an item falling out of her bag. "She has the little measuring thing," he explained.

"A glucose meter," Sherlock corrected. "Well done, Detective Campbell!"

Archie grinned back. Sherlock added bits of information he'd gleaned about the woman—widowed, nearsighted, retired nurse, had baked this morning—and how he had reached those conclusions, amazing his young apprentice with the depth and breadth of his knowledge.

"Sherlock," Archie asked, very seriously. "You don't actually _tell_ everyone what you deduced about them, do you?"

The detective sighed ruefully. "I used to. It didn't go over very well."

"What made you stop?" Archie wanted to know.

Sherlock stared at the water for a bit, unmoving as he gathered his thoughts. "For many years, I used deductions like weapons, stripping everyone bare of secrets before they could attack me. Some were impressed, and most were furious. It ensured I was left alone, especially at university."

Even a child could see that Sherlock had been bullied for his cleverness. Archie waited in silent solidarity.

"I didn't really stop until John came along. I could take one look at people and know exactly what they'd done and how, but the _why_ was harder to pin down. I'm not good with sentiment," he admitted. "John stopped me when I said things that were Not Good. I still noticed everything, of course, but I didn't say it aloud unless it was relevant to the case. And then I had to leave," he finished. "For two years, I was all alone. There was no one to listen to my deductions anyway, so I kept them to myself."

It wasn't quite true, since he'd shared his deductions with the John in his mind palace, but Sherlock was reluctant to explain _that_ to Archie. His mind palace was not the spotless library of information it had once been. Emotions had crept in, especially after the Fall, and even more so after John's wedding and the shooting.

"So," the detective suggested, clearing his throat. "Try not to offend people _too _much. A little is okay, but if you want to keep your friends, be smarter than I was."

The plea was earnest, uncomfortably so for Sherlock. So he did what he did best, and covered up his emotions with more deduction training.

"Okay! I'll pick someone this time, Archie. How about her?"

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Throughout this fic I'm trying to keep a balance between Sherlock the kid in an adult's body, and Sherlock the grown-up. I hope that's coming across. =P Anyway, I hope you enjoyed; please leave a comment if you're so inclined. See you next time!


	3. Chapter 3

**Food for Thought**

After the people at Regent's Park became too boring, Sherlock took Archie on a walking tour of central London, using his scarf to blindfold the boy at different sites, and teaching him to use all of his senses. The detective recorded the sounds of different streets, so Archie could identify them later. They smelled the plants in the parks and the River Thames from different bridges, memorizing London as only Sherlock could.

"Sherlock?" Archie asked finally, "can we get some food, please?"

Sherlock frowned. "What time is it?"

"Er—half one?"

Peering at his phone to confirm, the detective blinked in surprise. "Ah, sorry, Archie. I don't really eat at normal hours," he explained, sheepish. "I know just the place, though; follow me."

They walked a few more blocks until the familiar door of Angelo's popped into view. Heavenly smells wafted into the street, and Archie's stomach rumbled in anticipation.

Sherlock pushed open the door, and the tinkling bell brought them to the owner's attention.

"Sherlock!" he cried joyously, startling the nearest waitress. "Where have you been, boy?"

Without waiting for a reply, he rushed over to Sherlock's table and plucked the 'Reserved' sign off.

"Have a seat, lads. Who's this young fellow?" Angelo asked, inspecting Archie and then Sherlock. "You sly dog, I'd no idea you had a son!"

Archie blinked up at him from his seat. "I'm Archie. Sherlock's not my dad, he's a friend," he said sincerely.

The restauranteur rallied quickly. "Ah, and you couldn't ask for a better one," he told the boy. Leaning in, he whispered, "This man got me off a murder charge."

The boy's eyes went wide. "Really?"

Angelo nodded. "My wife was desperate, so she called Sherlock and he took my case. He gave the police all the proof they needed that it wasn't me that killed those men. Anything you want," he said, pointing to the menu, "on the house, boy. Are you on a case, Sherlock?" the man asked, knowing that Sherlock didn't eat while working.

"No," the detective answered. "I'm recovering from a gunshot to the chest, Angelo. Lestrade is not giving me cases yet."

The Italian cursed under his breath, saw Archie, and apologized immediately, making him giggle.

"No wonder you're skinnier than usual," he said finally, poking at Sherlock's arm. "Hospital food will sap the strength right outta you. I'll make your favorite, don't you worry. Wine?"

"Coffee," Sherlock supplied. "Bla—"

"Black, two sugars. I know," Angelo finished. "And you, Archie?"

"I'll have a Coke," Archie said shyly. "And the chicken parmigiana."

"Coming right up," the man promised, and left for the kitchen.

Once Angelo had gone, there was a silence as Sherlock looked at his phone, and Archie looked at Sherlock, his bright brown eyes curious.

"How did you solve his case?" he asked finally.

Sherlock raised an eyebrow at the boy's genuine interest. "I could tell that Angelo wasn't being entirely honest, so I did some digging. As it turned out, he _was_ guilty of a crime, but a lesser crime in a different part of the city. I found enough evidence to put him there at the time of the murders, and by so doing, gave him a rock-solid alibi."

"What was the evidence?"

"There was a bootprint left at the crime scene—man's work boot, size nine. I looked at the residue it left behind and found particulates in the dirt that are specific to the riverbank around Wandsworth Park. Angelo hadn't been anywhere near there, and an analysis of _his_ size ten shoes proved he'd been in the East End. I also found the tools he'd used to break into five cars, as well as a few things he had stolen from each of the vehicles."

Archie looked at his hero with new respect. "Wow."

The detective smiled. "Neat, isn't it? Then Lestrade called me to find the _real_ murderer, which I did in about nine hours."

They passed the next few minutes comfortably, chatting about other cases over a basket of fresh garlic bread. Unlike most of Sherlock's adult acquaintances, Archie knew how to ask the right questions, making him a delightful audience.

As the detective explained the intricacies of catching a jewel thief using his vast knowledge of tobacco ash, Angelo's oldest server Tony arrived with their piping hot meals. Archie's stomach growled loudly enough to startle the lady seated behind Sherlock.

"Enjoy, gentlemen," Tony said brightly, then left them to it.

For a while there was silence, except for the clatter of forks against Angelo's plates. Worn down by his injury, Sherlock gave in to his body's need for food and ate with genuine enjoyment. Archie had him beat when it came to enthusiasm, though. He practically inhaled his chicken and pasta, eating steadily and then mopping up the extra sauce with bits of garlic bread.

"Impressive," the detective said wryly, admiring the boy's empty plate. "You've won over Mrs. Hudson and Angelo in one day, Archie."

His brow furrowed. "By eating food?"

"Yes," Sherlock answered, poking at his food with a wry grin. "There's something about us skinny fellows that screams '_feed me!_' to every restaurant owner and little old lady, haven't you noticed? Eat a bit and they'll be your friends for life."

"Oi! There's a good lad!" Angelo cried, appearing as Archie cleaned the last bit of sauce off his plate. "You could learn something from young Archie, Sherlock," he added, clapping the poor detective on the back. The force of the impact made him wince.

"Angelo, if I wanted a scolding I could always ring my mother," Sherlock said dryly, although the other two saw the corner of his mouth twitching.

"Yes, but she's not here," Angelo replied, equally dry. "Archie, would you like some tiramisu or cannoli to take home?"

Archie considered the offer for a moment. "Thanks, but no. I dunno if I can eat any more."

The ex-car thief laughed. "Well, come back and visit us soon, eh? I'll make you my special layer cake."

"Okay," the boy agreed, grinning at his new friend.

"Right, best be off—lots to do," Sherlock said quickly, slipping some money under the salt shaker before Angelo could stop him. "Come along, Archie. Angelo, lunch was delicious as always."

Torn between pride at the praise and offense at the money, Angelo huffed, shook his head, and waved as the two curly-headed figures left the restaurant. Then, he picked up the ₤20 note and got back to work.

After all their walking, Archie was knackered and Sherlock not far behind. The detective steered his charge back to Baker Street, where a cheerful Mrs. Hudson hummed along to the radio as she scrubbed her kitchen floor.

"Hello, dears," she called out as she spotted them. "Where've you been, then?"

"We just had lunch," Archie replied, "and we walked around for ages."

"Well, that's better than making things explode upstairs," the landlady mused, "but William Sherlock Scott Holmes, if you wear down your body before you recover, _again_, I will kill you myself, do you hear?"

The diminutive woman looked rather threatening as she waved her cleaning rag in the tall detective's face.

"Don't worry, Mrs. Hudson," Sherlock answered, more warmly than he usually did. "We'll be upstairs all afternoon."

"I'll be watching," she warned, before giving Archie a smile. "Have fun, dear."

"I will," the boy replied, following Sherlock upstairs.

While Archie excused himself to use the bathroom, Sherlock set up his apprentice's next lesson. It had not been difficult for a former curious, experiment-friendly child to pick an activity for another curious child. Little Sherlock, aided by his genius brother and mother, had used and abused telescopes, chemistry sets, ants in the garden, and any scientifically interesting specimen that crossed his path. Adult Sherlock was much the same.

The boy returned as Sherlock placed the last test tube on the kitchen table.

"What's this?" Archie asked eagerly.

"I thought we could have some fun with an experiment," Sherlock replied, grinning. "Let's say Scotland Yard call me tonight to help with a case. They found a dead body, and next to it is a broken glass bottle of a mysterious white powder. It may be the murder weapon, and it may not. Come here," he ordered, slipping on some safety goggles and doing the same for Archie. His had an elastic strap that tightened, although they were still too large for the boy.

On the table he had several test tubes with white powder, and other compounds in beakers and tubes nearby, labeled in spiky handwriting.

"We'll run a series of tests, and see if we can identify the mysterious white powder."

Eagerly, Archie sat next to Sherlock.

"The first test is to see how the compound reacts with water. Take that pencil," he said, "and write down what happens when I add water to tube number one."

"What kind of stuff could happen?" Archie asked.

"Well, it depends on the compound," Sherlock explained. "It might dissolve completely, or partially. It could generate an exothermic reaction, which would make it really hot. It could change color, or do nothing, and just stay at the bottom of the test tube."

Archie watched carefully as Sherlock added a few drops of sterilized water to the first test tube. The white substance dissolved quickly, leaving a clear liquid. Archie wrote that down, and then Sherlock took his hand and held it close, but not touching, the test tube.

"Wow!" said Archie, surprised by the heat.

"Now we can rule out simple aspirin," Sherlock said, bouncing on the balls of his feet and smirking.

Archie watched his excited babysitter with amusement. "Cool. What's next?"

"Let's try some ethanol," the detective suggested, picking up the second tube.

Before he squeezed the pipette, he called out "Go away, Mycroft."

Before Archie could ask who Mycroft was, the man appeared dramatically in the sitting room, dressed in a suit and carrying an umbrella.

"You've become quite rude in your convalescence, brother mine," he drawled, "although now that I think of it, you were always that rude."

"I'm busy here," Sherlock insisted, putting drop by drop of ethanol into his test tube with exaggerated movements. "Archie, watch the reaction again."

Archie did so. This time there was no heat, and the white powder did not dissolve completely. He wrote that down.

"Ah, your apprentice," Mycroft said lazily. "Young Archie, was it?"

The boy in question looked up. "You know about me?"

"Mycroft knows everything, like the nosy big brother he is," Sherlock told him.

It didn't take a genius to see his hero didn't like his older brother. Still, as a smart young boy, Archie didn't see the point in antagonizing the other man.

"Are you a detective too?"

He ignored Sherlock's derisive snort.

Mycroft smiled slightly, but shook his head. "I work for Her Majesty's government," he answered. "I leave the crime-solving to my brother."

"How generous of you," Sherlock replied mockingly. "_Now_ will you go away?"

"But I just arrived," the older Holmes brother answered, making himself comfortable on Sherlock's green armchair. "I've come all this way to check on my injured little brother, so I'll be staying a while. Carry on with your experiment; don't mind me."

Sherlock and Archie continued their task, ignoring the presence of Mycroft Holmes. He watched as they identified the powder as sodium hydroxide, then started over with a new compound (caffeine, obviously). Not until the fourth compound did Archie show signs of boredom, and he only gave up when Sherlock had run out of litmus paper and acetone.

"_Myc, Myc, I know what it is! It's bicarbonate of soda!" said a curly-haired boy excitedly. "Am I right?"_

"_Well done, Sherlock!" their mother said, beaming with pride._

"_You should have figured it out ages ago," Mycroft muttered. "You're so stupid, Sherlock."_

"_I am not!" pouted his little brother._

"_Mycroft, don't be ridiculous! He's a bright little boy for his age," Margaret Holmes scolded._

It was impossible to see little Archie and not remember Sherlock at the same age. Mycroft was fascinated to watch his brother's patient instructions to the boy, when he was not patient with _anyone_, save perhaps John Watson. An uncomfortable nostalgic feeling tickled his brain.

Without the bother of saying goodbye—he knew how Sherlock would respond to _that—_Mycroft left his brother's flat. Little Archie Campbell was in surprisingly good hands.


	4. Chapter 4

Here it is, the last chapter in this little story. Say farewell to little Archie, and enjoy!

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**4\. The Doctor and the Two Detectives**

John returned at six o'clock, emotionally drained as he always was after visiting Harry. He dragged himself up the stairs to the B flat, ready to face Sherlock's deductions. As he opened the door and peered inside, he blinked and squinted in confusion.

Two Sherlocks?

Either John was going mad, or there were two curly, dark-haired, purple-shirted Sherlocks peering at the floor. One was rather shorter than the other—oh!

With a jolt, John recognized the smaller one as Archie. The memory of his wedding caused an unpleasant lump in his throat; he pushed the thought away.

"What's this, then?" he asked casually, leaving his coat on the hook.

Sherlock looked up. Not counting the giddy, post-case high, this was the happiest John had ever seen him. He was grinning and his eyes were bright. Then he saw his flatmate, and his expression dimmed. The doctor was sure Sherlock could read every one of Harry's excuses and drunken rants in John's grey-blond hair, tousled by frustrated fingers.

"Doctor Watson!" chimed Archie happily. "We made our own board game, look! It's like an extreme Cluedo, for _real_ detectives."

"That's right," Sherlock agreed. "All of London is our game board, from Scotland Yard to the filthiest hovels and the largest mansions."

Curious, John looked at the 'board game'. Its base was an old street map of London as big as a rug, so large that both armchairs and the coffee table had been moved to make room for it. On the map, someone had drawn numbers and letters in marker. A stack of blue cards lay on top of Scotland Yard, and yellow cards lay over the Tower of London. John counted three separate pairs of dice, and chessmen serving as the game pieces. Red and green cards were scattered all over the map, and the patient from the Operation board game lay over the Thames.

"Looks complicated," John said finally.

"Only as complicated as a detective game should be," Sherlock said, throwing a scathing glare at the Cluedo board pinned to the mantel. "The numbers are possible crime scenes. The letters are helpful places to gather clues, such as Barts, the victim's house, and places where my homeless network is known to congregate."

"Yeah," Archie joined in. "The green cards are victim description cards, and the red cards are suspects. Blue cards are interview questions and answers the police got for that suspect, and yellow cards are pieces of evidence you collect."

"And unlike _that_ abomination," Sherlock finished, jabbing his thumb at the fireplace, "it's possible for a crime to have multiple guilty parties, or none at all. Accidental death and suicide are allowed."

"I see." John hid a smile by heading to the kitchen for some tea. "You know, Sherlock, now that you're a hero again, you could probably sell that idea to Hasbro and make it an official Sherlock Holmes board game. You'd make a tidy profit."

He put the kettle on and headed back to the living room.

"You're assuming everyone would like it," Sherlock said, suddenly weary. "Except for Archie here, kids these days only want electronic games that involve shooting things, or whacking at things with magical swords. This game requires _thinking_."

"He's got a point, you know," Archie told John sagely. "All my friends want to play is _Call of Duty_ or _Grand Theft Auto_."

"Well, I'm glad _you_ don't, mate," John said fondly, ruffling his curls. "It's nice for Sherlock to see we're not all idiots."

"Nonsense, John," Sherlock protested. "I have you for that."

That was not what he'd said during the pink lady's case, but John held his tongue. For a man who had probably used up his yearly supply of niceness at John's wedding, that was a decidedly flattering statement. In Sherlock's typically backhanded way, of course. He'd still take it.

"Do you want to play?" Archie offered eagerly. "I won the last one; Sherlock got one of the red herring cards and wasted three turns on a bad lead."

"Yes, do join us, John," Sherlock offered. "Archie is the white bishop there, and I'm the black queen."

He offered John a white knight.

"Yeah, alright," said John, taking it, "if we can get a takeaway first, and if you explain the rules thoroughly."

Sherlock looked at Archie. "What are you hungry for, Consulting Detective Campbell?"

The soldier watched the boy's face light up at the title and fought a smile. For such an antisocial man, Sherlock made an incredible babysitter. "Er—Chinese?"

John reached into the nearest cupboard and pulled out the takeaway menus, handing the correct one to Archie.

"I'll have my usual," Sherlock said lazily.

"What's your usual?" Archie asked, still reading the menu.

"The Szechuan stir-fry with noodles," John and Sherlock answered together, to Sherlock's amusement and John's surprise. He hadn't realized just how many tiny details about Sherlock he still remembered.

"Eugh," the little boy replied, sticking out his tongue and scrunching up his nose. "I'll have the Peking chicken with rice, Dr. Watson. And a Coke."

"Right," said John, taking back the menu. Once he'd had all of these numbers on his phone, but he'd deleted them after moving out of 221B. Instead, John read the number from the back of the menu and dialed, as he'd done so many times before. Even after two years, the lady who answered the phone was the same. It was almost soothing, to fall back into these familiar patterns with Sherlock and the old flat.

* * *

When Archie's mother came to collect him an hour later, laden with shopping bags and exhausted, a smiling Mrs. Hudson showed her upstairs and opened the door to 221B. Peering inside, Cynthia saw Sherlock and John on the floor, playing a gigantic board game with her son. Empty takeaway boxes lay on the coffee table, stacked precariously and forgotten.

John rolled the dice, oblivious to Cynthia's presence. "Two again! I swear, Sherlock, if you're giving me loaded dice, I'm going to shove them up your skinny—"

"Shut up and walk back to the crime scene, Dr. Watson," Sherlock ordered. "Clearly you haven't found all of the clues yet."

Archie looked up, grinning, and saw his mother. "Mum!"

Sherlock and John looked as well. "Hi, Cynthia."

"Hello," she said, stepping into the flat. "I hate to interrupt you boys when you're having fun, but it's getting late. It's time to go, Archie."

"Aw, just when it was getting good," he sighed, leaving his cards and standing up slowly. "I was _this_ close to catching the bad guy and winning the game, Mum! I had _four_ pieces of solid evidence, a murder weapon, _and_ witness testimony!"

"It'll keep," Sherlock said encouragingly. "I won't let anyone touch the board until you come for another visit."

John raised an eyebrow. It was a nice gesture for Sherlock to do, but seriously? This thing was bigger than their living room!

Before John could object, Sherlock dug up a roll of Sellotape. He taped all of the pieces to the map, and moved the cards off, keeping them in separate piles. As the other three watched, he stood in one fluid motion, crossed the room, and pinned the giant map to his 'case' wall, covering the yellow smiley face and bullet holes.

Archie hugged him impulsively. "Thanks, Sherlock. You're the best."

Sherlock smiled down at the boy. "I know."

He winked down at Archie, who laughed.

"Any trouble?" Cynthia asked, more out of politeness than anything. She could see there hadn't been.

"None whatsoever," the detective answered. "Archie is welcome here anytime."

As the woman reached into her purse for her wallet, Sherlock stopped her. "No. I'm a friend, not a babysitter."

For a moment, John thought Cynthia would hug his flatmate too. Then she gave him a soft smile.

"I owe you, then," she said finally. "Archie, get your coat on, love."

Grumbling, Archie shrugged on his coat and followed his mother downstairs, stopping when Mrs. Hudson claimed a hug. Sherlock and John walked them out, and waved as the mother and son left in a taxi. Archie chattered at his mother all the way, recounting his adventures with Sherlock.

"Well!" sighed Mrs. Hudson as they shut the door. "How did you like your new apprentice, Sherlock?"

Sherlock raised an eyebrow. "I wouldn't make him _my_ apprentice if he were anything but brilliant."

Their landlady giggled. "You know, Sherlock, between the hair and the shirt, I thought I was looking at your son this morning. The thought wasn't as frightening as one might think," she added wistfully.

"What, adding another Holmes to terrify the world, and granting my mother what she wants the most? Perish the thought immediately," he answered, bounding up the stairs. "Good night, Mrs. Hudson."

"Night, Mrs. H.," John added, following Sherlock.

Without a word, Sherlock tidied the living room, moving his chair and John's back into their usual places. The stacks of game cards were labeled neatly and placed in a drawer, though the pile of takeaway rubbish stayed where it was. After all, Sherlock was Sherlock.

"Well, that was fun," said John, sinking into his chair. "How did Archie come to be here?"

"Cynthia had some divorce issues to settle," Sherlock explained from the sofa, leaning all the way back and staring at the ceiling. "She rang this morning and asked if I could watch Archie for a few hours, and I told her to make it a day."

John's surprise was evident. "She asked for a few hours, and you _volunteered_ to watch the kid all day? Are you insane?"

The detective shrugged. "What else was I supposed to do while you were out? He's a smart kid, and Gabriel is still upset that I won't say who shot me, so I have no cases."

John chose to ignore the last bit and focus on what was safe. "_Greg_, you idiot. Greg!"

"Whatever."

There was a moment of silence, as John caught up with the news on his mobile, and Sherlock lay on the sofa, staring at nothing and thinking.

"Right, I need a shower," the doctor said finally. "Don't do anything stupid while I'm gone."

Sherlock's answer was a light snore. John shook his head, amused, and covered up his best friend with the nearest blanket. It wasn't cold enough for a fire just yet, but he was taking no chances with the detective's recovery.

Once Sherlock was covered up to his nose, the good doctor had his shower.

* * *

Thanks so much for reading and reviewing, everyone! While this story is over, the _A Chair In Its Proper Place_ series continues with the next installment (after John is done showering), **Friendly Advice**.


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